Multichannel Sonic Data

ODP logging contractor: LDEO-BRG

Hole: 735B

Leg: 118

Location: SW Indian Ridge (SW Indian Ocean)

Latitude: 32° 43.395' S

Longitude: 57° 15.959' E

Logging date: December, 1987

Water depth (as seen on logs): 731 mbrf

Total penetration: 500.7 mbsf

Total core recovered: 434.8 m (86.8 %)

TOOL USED: MCS (Multichannel Sonic Tool)

Recording mode: 1 transmitter and 12 receivers, each spaced 15 cm apart.

Remarks about the recording: none.

The Multichannel Sonic data were originally acquired with acquisition software produced in-house, residing on a Masscomp computer.

Each of the 12 waveforms consists of 1000 samples, each recorded at a sampling rate of 5 microsec, at depth intervals of 1 m (downlog) and 0.3 m (uplog). The original data has been loaded on a Sun system and then converted into binary format.

Each line is composed of the entire waveform set recorded at each depth, preceded by the depth. In the general case of 12 waveforms with 1000 samples per waveform, this corresponds to 1 + 12x1000= 12001 columns. In this hole, the specifications of the files are:

Number of columns: 12001

Number of rows: 25 (downlog upper section)

Number of rows: 227 (downlog lower section)

Number of rows: 1196 (uplog lower section)

Number of rows: 47 (uplog middle section)

Number of rows: 378 (uplog upper section)

All values are stored as 'IEEE floating point'.

Each file can be viewed directly as an image with Spyglass transform or NIH image on Macs and PCs, or Fortner transform or Khoros on UNIX) - where it has to be opened as either 'raw' or 'binary matrix'. Any image or signal-processing package should also allow viewing it.

The following files have been loaded:

118-735B_mcsdu.bin: 930-954 mbrf

118-735B_mcsdl.bin: 995-1220.9 mbrf

118-735B_mcsupl.bin: 858.2-1216.6 mbrf

118-735B_mcsupmid.bin: 846.2-860 mbrf

118-735B_mcsupu.bin: 745-858 mbrf

The sonic waveform files are not depth shifted to a reference run or to the seafloor. For depth shift to the sea floor, please refer to the DEPTH SHIFT section in the standard log documentation file.

NOTE: For users interested in reading and converting the data to a format more suitable for their own purpose, the fortran declaration used to open the file *.bin would be:

open (1, file = *.bin,access = 'direct', recl = 4*(1+nwav*nsamples))

where nwav is the number of waveforms (12) and nsamples the number of samples per waveforms (see above).

If the total number of depths where waveforms have been recorded is ndepth (for a 150 m interval with data every 15 cm, ndepth would be 1000), a generic loop to read the data would be

do k = 1, ndepth

...

read(1, rec=k) z, (data(i), i = 1, nwav*nsamples)

...

enddo

In such a case, the file dimensions will be ndepth rows by nwav*nsamples+1 columns

For further information about the logs please contact:

Cristina Broglia

phone: 845-365-8343

fax: 845-365-3182

email: Cristina Broglia

Gilles Guerin

phone: 845-365-8671

fax: 845-365-3182

email: Gilles Guerin